Association between clinical outcomes and local treatment in stage IV non‐small cell lung cancer patients with single extrathoracic metastasis

BACKGROUND: Local treatment (LT) such as radiotherapy and metastasectomy on metastatic sites may improve outcomes in oligometastatic NSCLC patients, but more data are necessary to support LT in oligometastatic diseases. Patients with single extrathoracic metastatic lesion are more likely to benefit from local therapy. In this study, we evaluated the impact of LT in NSCLC patients with a single extrathoracic metastatic lesion. METHODS: Data were obtained from the Korean Association for Lung Cancer Registry (KALC‐R), a database created using a retrospective sampling survey by the Korean Central Cancer Registry (KCCR) and the Lung Cancer Registration Committee. RESULTS: A total of 787 NSCLC patients with a single extrathoracic metastatic lesion were evaluated. In the multivariate analysis for OS, age, female sex, poor performance score, squamous histological subtype, LT, and initial treatment modality showed significant associations. Regarding LT, groups that underwent curative LT were significantly associated with better OS compared to groups that did not undergo LT (p = 0.011, HR 0.448, 95% CI: 0.242–0.829). In the multivariate analysis of patients who underwent LT, poor performance score, initial treatment modality, and T stage were independently associated with poor OS. Compared to the T1 stage, T3 stage showed an HR of 2.470 (95% CI: 1.309–4.663; p = 0.005) and T4 stage showed an HR of 2.063 (95% CI: 1.093–3.904; p = 0.026). CONCLUSION: In NSCLC with a single extrathoracic metastatic lesion, LT, especially for curative purposes, has an independent association with OS. Moreover, among the patients who received LT, factors such as T stage, poor performance score, and initial treatment modality were significantly associated with OS.